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| Renewable Energy Discussion on various alternative energy, renewable energy, & free energy technologies. Also any discussion about the environment, global warming, and other related topics are welcome here. |
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Your reasoning is very good. A while ago I made a thread about a similar concept but which is mechanical.
Create energy with conservation of momentum law. It makes sense that the flux remains constant so changing L should change I. |
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MIT doing it with a capacitor?
The energy formula is E=½*C*U² and the "momentum" formula is Q=C*U When the charge Q is constant and capacitance C drops the voltage U rise. What happens to the stored energy? YouTube - MIT Physics Demo -- Adjustable Capacitor with Dielectric /Hob |
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@nilrehob: there's something we forgot. The parameter we adjust, windage, in order to change inductance has actually a squared relationship in our inductance equation and a linear one in flux. Flux isn't L*I but L*I/N. Here are some relevant equations for a straight solenoid:
![]() That means if we for instance halve the amount of windings the current would double so flux is conserved. However our inductance will actually drop 4 times, not 2. Compensating for the increased square amperage in the energy equation. In other words the windings do not have a linear relationship with mass. But a squared one. So this defeats our point. However there are other parameters that do have this linear relation. Area and permeability. If you can change those during operation the change would directly be reflected in an equal change of current through conservation of flux. And since they have a linear relation in both the flux and energy equation you will thus see an increase in inductive energy. Last edited by broli : 01-08-2011 at 12:00 PM. |
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@broli
Yes, youre right, the inductance is not added as H+H when sharing core. This is however only to our benefit, as theoretical COP is Hin/Hout. (1) This comes from COP = Eout/Ein = ½*Hout*Iout² / ½*Hin*Iin² (2) since (if) flux is constant Hout*Iout = Hin*Iin (3) from (3) you have Iout = Hin*Iin / Hout (4) put that into (2) and you have ½*Hout*(Hin*Iin / Hout)² / ½*Hin*Iin² (5) simplify this and you get Hin/Hout (1) But maybe I need to digest your point some more. /Hob Last edited by nilrehob : 01-08-2011 at 11:47 AM. |
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Quote:
![]() From conservation of flux we know that the product N*I remains constant. So that means energy will remain constant as well no matter the combination. |
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@broli
Doh! So lets use a toroid with a ferrite core, all flux is now in the core, in the Weiss-domains of the ferrite, now this has to work, please... BTW, doesn't ferrite have a kind of delay for getting magnetized and demagnetized? Whats it called? If there is one wouldn't it dictate the maximum switch-off-time? /Hob |
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Well, tomorrow I plan to make a toroidal transformer.
I don't have a proper or fancy core so I'm going to use a plastic-coated "garden-wire" which has some iron in it it seems. Maybe I shall do the core as a torus instead, with the coil-wires inside? First wind the coil-wires like an air-core coil, and then wind the garden-wire around it? /Hob |
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When you use a core you change the game, because then you start to play with permeability. Permeability change would truly change energy because it has both a linear relation with flux and energy. But the problem is that we can't instantly switch between permeabilities like we could between winding amount...or can we? For instance a ferromagnetic material losses its magnetic properties when it's heated above a point. You will gain energy through conservation of flux, the heat will go nowhere, so in theory you can extract the increased inductive energy, recapture the heat and start all over. But using heat would be terribly inefficient.
Last edited by broli : 01-08-2011 at 06:43 PM. |
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Does H stand for Henry or the H field?
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Just analyze the equations carefully. And look at the raw parameters that make up the inductance of a solenoid. For instance I just noticed we completely ignored coil length so far. If you have two coils on top of each other, with the same amount of windings but one longer than the other. When energizing the short one and opening the switch and letting the long one collect the inductive energy what you did is instantly and effortlessly double the length, this would halve the flux, so conservation of flux kicks in and doubles current. Since inductive energy is linearly proportional to 1/length as well you should see an increase.
![]() Last edited by broli : 01-08-2011 at 07:15 PM. |
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You're right. Then one solution would be using thicker wire for the secondary and keep the same number of turns (but not wind them together).
So which part of the kapagen do You think we are looking at? /Hob Last edited by nilrehob : 01-09-2011 at 08:45 AM. |
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The trick is to try and trap as much flux as possible. That's why a closed loop core like a toroid could be beneficial. It's well known that spacing of the windings of the toroids affects the inductance significantly: http://users.catchnet.com.au/~rjandu...s/wind_deg.gif I would suppose the bigger the toroid the more you can space the windings apart and increase the flux difference. If we suppose most of the flux gets trapped. Then switching from a densely wound winding to a spaced out one, will give maximum flux difference and thus shoot the current up to conserve it. This all without changing the amount of windings. So inductive energy has to go up too. |
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Great pic of the toroid, thanks!
But I must admit there is still an enigma left in the formulas for me. We have the definition of the unit Henry: ![]() Which gives you Wb=H*A, or Φ=L*I, right? Then we have the definition of flux: ![]() Combine them and you get L=μ*N*A/l But that's not right! It should be ![]() Where is the error? /Hob |
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Quote:
It's easier to see this if you derive the "inductance" from Faraday's law (which is where it comes from in the first place): ![]() Last edited by broli : 01-09-2011 at 12:56 PM. |
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Yes, I just found it myself
L = N × d Φ / d I at Magnetism: quantities, units and relationships /Hob |
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Now, back to your toroid-pic:
![]() This reminds me very much of the toroid in the vid starting this thread: This is it ! /Hob |
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So what about three parallel windings,
each occupying 120deg of the toroid and having N turns each for input, and then a wider and thicker winding with N turns on top (or under?) as output? But on the other hand, parallel windings lower the inductance ...I have to dig up the Bob Boyce documents lying on my hard-drive somewhere. /Hob Last edited by nilrehob : 01-09-2011 at 01:27 PM. |
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Quote:
![]() ![]() theta*r is really just definition of arc length. In textbooks theta is always equal to 2pi radians which is 360°. Last edited by broli : 01-09-2011 at 01:39 PM. |
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Tesla Toroid
Hi nilrehob and broli, Good to see you guys doing the math on this, the more people that look into this the better. I thought I would give you guys this link to look at. If you look at page 110 figure 92 and 93, also page 111 figure 94.
Page 110 figure 92 and 93 is the Tesla transformer/converter and page 111 figure 94 is the same thing with generator attached. The section "High Frequency Polyphase Transformer" starts on page 109, it's very interesting, in my opinion it can be a "flux flywheel generator" and that is kinda how it's descibed in there. Tesla used quad primaries with the oposite pairs series connected and fired 90 degrees out of phase, which was actually 180 out of phase on the generator. I think, maybe you guys can decifer that better than me. He also used quad secondaries and he shows that the secondaries can be connected however is needed or desired, it's a very cool setup. And he also used iron shielding wire aswell sometimes. The inventions, researches and writings of Nikola Tesla, with special reference to his work in polyphase currents and high potential lighting : Martin, Thomas Commerford, 1856-1924 : Free Download & Streaming : Internet Archive Enjoy Cheers |
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So it all boils down to a theoretical COP=θin/θout, right? /Hob Last edited by nilrehob : 01-09-2011 at 02:32 PM. |
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Correct, and it's a way to have a "thicker" wire like you mentioned earlier without really having to use a thicker wire.
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Quote:
Primary small angled coil energized and then letting it discharge into a cap. Then same experiment but this time you put the cap on the big angled coil. And hopefully you'll see more voltage there in the cap. The other experiment needs you to energy both coils in series and discharge them in series, and comparing it to only opening the switch on the small angled coil and discharging through the second in the same cap. |
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